The present invention relates generally to measuring physiologic parameters of a patient, and more particularly, to systems, methods and devices for measuring and deriving physiologic parameters relative to various environmental parameters.
Medical devices are known that can be implanted within a patient's body for monitoring one or more physiological parameters and/or to provide therapeutic functions. For example, sensors or transducers can be placed in the body for monitoring a variety of properties, such as temperature, blood pressure, strain, fluid flow, chemical properties, electrical properties, magnetic properties, and the like. In addition, medical devices can be implanted that perform one or more therapeutic functions, such as drug delivery, cardiac pacing, defibrillation, electrical stimulation, and the like.
In many cases, the implanted medical devices (“IMDs”) are configured or adapted to communicate with external controllers or programmers, for example, to communicate data between the IMD and the external programmers, and/or to activate or otherwise control the IMDs. Typically, the IMDs can communicate with the external programmers via a wireless communication link, such as an RF communication link, or the like.
As mentioned above, IMDs can be configured to measure or sense a number of different parameters in the body. One parameter of particular interest is blood pressure. The implantable biosensors that measure pressure deep within anatomical structures, however, typically can only communicate the absolute pressure associated with the immediate anatomical environment. These devices are not capable of communicating gauge pressure because they are confined and sealed away from the ambient pressure external the body. In most cases, it is gauge pressure and not absolute pressure that is sought to be known, since the body regulates its activities based on the ambient pressure. Gauge pressure may be determined by correlating the absolute pressure with the ambient pressure. Similar situations exist for other parameters, as well, such as temperature.
Thus, a need exists for systems, methods, and/or devices for adjusting measured physiologic parameters, such as pressure, temperature and others, based on ambient or other environmental conditions.